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1 jermar 1 
/*
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 * Copyright (C) 2001-2004 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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383 jermar 29 
#include <synch/spinlock.h>
111 palkovsky 30 
#include <arch/atomic.h>
153 jermar 31 
#include <arch/barrier.h>
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#include <arch.h>
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#include <preemption.h>
195 vana 34 
#include <print.h>
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#include <debug.h>
1 jermar 36 
 
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#ifdef __SMP__
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383 jermar 39 
/** Initialize spinlock
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 *
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 * Initialize spinlock.
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 *
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 * @param sl Pointer to spinlock_t structure.
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 */
1 jermar 45 
void spinlock_initialize(spinlock_t *sl)
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{
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    sl->val = 0;
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}
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#ifdef DEBUG_SPINLOCK
383 jermar 51 
/** Lock spinlock
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 *
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 * Lock spinlock.
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 * This version has limitted ability to report
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 * possible occurence of deadlock.
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 *
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 * @param sl Pointer to spinlock_t structure.
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 */
1 jermar 59 
void spinlock_lock(spinlock_t *sl)
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{
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    int i = 0;
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    __address caller = ((__u32 *) &sl)[-1];
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223 jermar 64 
    preemption_disable();
1 jermar 65 
    while (test_and_set(&sl->val)) {
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        if (i++ > 300000) {
15 jermar 67 
            printf("cpu%d: looping on spinlock %X, caller=%X\n", CPU->id, sl, caller);
1 jermar 68 
            i = 0;
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        }
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    }
383 jermar 71 
 
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    /*
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     * Prevent critical section code from bleeding out this way up.
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     */
153 jermar 75 
    CS_ENTER_BARRIER();
1 jermar 76 
 
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}
383 jermar 78 
 
1 jermar 79 
#else
383 jermar 80 
 
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/** Lock spinlock
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 *
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 * Lock spinlock.
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 *
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 * @param sl Pointer to spinlock_t structure.
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 */
1 jermar 87 
void spinlock_lock(spinlock_t *sl)
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{
223 jermar 89 
    preemption_disable();
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1 jermar 91 
    /*
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     * Each architecture has its own efficient/recommended
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     * implementation of spinlock.
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     */
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    spinlock_arch(&sl->val);
383 jermar 96 
 
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    /*
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     * Prevent critical section code from bleeding out this way up.
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     */
153 jermar 100 
    CS_ENTER_BARRIER();
1 jermar 101 
}
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#endif
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383 jermar 104 
/** Lock spinlock conditionally
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 *
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 * Lock spinlock conditionally.
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 * If the spinlock is not available at the moment,
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 * signal failure.
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 *
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 * @param sl Pointer to spinlock_t structure.
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 *
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 * @return Zero on failure, non-zero otherwise.
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 */
1 jermar 114 
int spinlock_trylock(spinlock_t *sl)
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{
153 jermar 116 
    int rc;
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223 jermar 118 
    preemption_disable();
153 jermar 119 
    rc = !test_and_set(&sl->val);
383 jermar 120 
 
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    /*
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     * Prevent critical section code from bleeding out this way up.
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     */
153 jermar 124 
    CS_ENTER_BARRIER();
223 jermar 125 
 
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    if (!rc)
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        preemption_enable();
153 jermar 128 
 
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    return rc;
1 jermar 130 
}
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383 jermar 132 
/** Unlock spinlock
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 *
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 * Unlock spinlock.
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 *
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 * @param sl Pointer to spinlock_t structure.
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 */
1 jermar 138 
void spinlock_unlock(spinlock_t *sl)
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{
383 jermar 140 
    ASSERT(sl->val != 0);
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    /*
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     * Prevent critical section code from bleeding out this way down.
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     */
153 jermar 145 
    CS_LEAVE_BARRIER();
383 jermar 146 
 
1 jermar 147 
    sl->val = 0;
223 jermar 148 
    preemption_enable();
1 jermar 149 
}
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#endif